By Richard Black
BBC News Environment Correspondent
The United Nations is to set up a task force to investigate the effects of climate change on regions like the Himalayas.
The world's highest mountain, Everest, could one day be nothing but rock
The decision came at the annual meeting of the United Nations Educational, Scientific and Cultural Organization's (Unesco) World Heritage Committee, which declared that climate change does pose a threat to natural and cultural heritage sites.
The initiative could result in a legal obligation on governments around the world to cut emissions of greenhouse gases, as the only way to protect these sites.
Environmental campaigners applauded the British government for its role in pushing the decision through.
"I'm delighted that the Committee has decided to investigate the impact of climate change on world heritage sites," Peter Roderick, Director of the campaign group Climate Justice, told the BBC News website.
"The jury's still out, and I'm not sure the urgency has been fully grasped; but at least it keeps alive the hopes that Everest, the Peruvian Andes, and the Belize Barrier Reef can be enjoyed by future generations."
Climate Justice co-ordinated a campaign by environmental groups in Nepal, Peru and Belize to have three existing world heritage sites in these countries put onto Unesco's "danger list".
They submitted petitions claiming that the Sagarmatha National Park in the Himalayas, the Huascaran National Park in Peru and the Belize Barrier Reef are being critically affected by climate change.
If the World Heritage Committee had accepted the argument fully at its annual meeting in Durban, South Africa, the 180 countries which have ratified the World Heritage Convention would effectively have been obliged to reduce greenhouse gas emissions.
The wording of the Convention means they accept that the international community is responsible for protecting world heritage sites, vow to preserve the sites for future generations, and promise not to take any action which would damage them.
Sir Edmund Hillary is becoming very worried about Everest
The Committee - which administers the Convention - stopped short of danger-listing the three sites, instead deciding to set up its task force, which will report by next year's Committee meeting; Britain will host the task force's first gathering.
The Committee did agree that "the impacts of climate change are affecting and are likely to affect more World Heritage properties, both natural and cultural. [So nations should] use the network of World Heritage Sites to highlight the threats posed by climate change..."
Before the meeting began, one of the first two men to climb Mount Everest, Sir Edmund Hillary, had given his backing to the campaign, issuing a statement saying that "the warming of the Himalayas has increased noticeably over the last 50 years.. this has caused several and severe floods from glacial lakes, and much disruption to the environment and local people."